Method checkMx

app/src/main/java/eu/faircode/email/DnsHelper.java:117–130

(Context context, Address[] addresses)

    }

    static void checkMx(Context context, Address[] addresses) throws UnknownHostException {
        if (addresses == null)
            return;

        for (Address address : addresses) {
            String email = ((InternetAddress) address).getAddress();
            String domain = UriHelper.getEmailDomain(email);
            if (domain == null)
                continue;
            DnsRecord[] records = _lookup(context, domain, "mx", CHECK_TIMEOUT);
            if (records.length == 0)
                throw new UnknownHostException(domain);
        }
    }

    @NonNull
    static DnsRecord[] lookup(Context context, String name, String type) {